A heart pacemaker is generally implanted subcutaneously in the chest wall along with a lead for conducting electrical signals, such as stimulating pulses, between the pacemaker and the heart. The lead is surgically implanted through a vein leading to a cavity of the heart. A typical heart lead includes one or more spirally coiled wires having a hollow inner passageway that extends the entire length of the coiled wires. The coiled wires are surrounded by a flexible tube or coating comprising, for example, silicone or polyurethane for insulating the wires from body fluids as well as each other. However, one problem is that, over time, fibrotic tissue commonly encapsulates the heart lead especially in areas where there is low velocity blood flow. When small diameter veins through which the lead passes become completely occluded with fibrotic tissue, separating the lead from the vein is difficult and causes severe damage to or destruction of the vein. Furthermore, the separation is usually not possible without restricting or containing the movement of the heart lead.
In most cases, the useful life of a heart lead lasts for many years. However, should the heart lead become inoperative due to corrosion or other effects of body fluids or should another heart lead be desired, the existing heart lead is typically left in place and a new heart lead is implanted through another vein. One problem with leaving an implanted heart lead in place, particularly in the heart, is that the lead partially restricts the operation of the various heart valves through which the lead passes. If several leads passing through a heart valve are left in place, the operation of the heart valve and the efficacy of the heart is significantly impaired.
Another problem associated with leaving heart leads in place, particularly in blood vessels, is that an infection may develop around the lead, thereby requiring surgical removal. Surgical removal of the lead from the heart involves open heart surgery which is complicated, risky, and costly.
One method for transvenous removal of a heart lead involves a prior art heart lead removal tool that utilizes a hollow, rigid tube and a beveled rod tip for engaging and deforming the coiled structure of the heart lead. However, when the heart lead cannot be removed because of some complication, a serious problem is that the tip of the tool is locked in place and cannot be removed from the heart lead. As a result, the tool and heart lead must be surgically removed. Furthermore, the rigid tube of the tool can easily puncture a blood vessel or a heart cavity wall.
Another method is to transvenously extract the heart lead manually without the aid of a tool. Such method is possible only when the lead has not ben encapsulated in a blood vessel. Even then, this method has a number of problems. First, when the polyurethane or silicone insulation covering is damaged, the lead covering can sever and cause the coiled structure of the lead to unwind and to damage the heart and blood vessels. Secondly, both the lead coil and covering can sever in the heart or a blood vessel and thus require surgical removal. Thirdly, most heart leads typically include tines or a conically shaped tip for securing the distal end of the heart lead to a heart cavity wall. After fibrotic tissue has encapsulated the tines or conically shaped tip, manual removal of the heart lead tip from the heart cavity wall may cause an inward extension or inversion of the wall, or even worse, permanent damage to the heart such as tearing a hole in the heart cavity wall.